Members of the Association of Principals of Vocational Schools and Community Colleges have complained of increased workloads from administration, disciplinary and other duties associated with recent laws.
The association represents the principals of the 243 second-level schools run by the VECs, many of which also run adult and further education programmes.
A report to its annual conference in Limerick showed that 66% of the 184 principals who replied to a survey would leave their principal's post if they had a viable alternative.
The figure was 72% for those with more than five years' service but just under half among shorter-serving school heads.
Association president Tom Hughes said it was clear that management and middle-management structures were not intended to cope with the situation now arising.
"I will be advising our parent body, Teachers' Union of Ireland, that additional management posts need to be created to support principals and their deputies, but not at the expense of teaching hours," Mr Hughes said.
He said a spate of legislation, including the Education Act, the Education (Welfare) Act, the Equal Status Act and the Vocational Education (Amendment) Act, had brought about added responsibilities.
"Much of this legislation is to be welcomed for placing much of our education system on a statutory footing for the first time, but the question must be asked who is going to do all of this new additional demanding work?"
Mr Hughes said a principal's working week was further lengthened by a row over supervision and substitution this year, which is still causing problems in some schools. TUI members have accepted a package to be paid for the work, and ASTI members are balloting on the same deal.
"A positive outcome in this regard would provide much-needed relief to our members in dual union schools and hopefully mark the beginning of the end of this long running, intractable and damaging dispute," he said.
Earlier, an education expert told the conference that teachers needed to rethink their methods to keep students interested.
Sarah Moore, dean of teaching and learning at University of Limerick, made her comments in the wake of an OECD report showing 67% of Irish 15-year-olds often felt bored in school.
"I'm very suspicious of the corporatisation of the education system, if you use students as customers, you might as well view them as products," Ms Moore said.
She said research at UL showed third-level graduates said their best lecturers were those who kept them engaged and interested, and the same could be applied to second-level students.